[gpaw-users] dense k point sampling

[Ivano Eligio Castelli]

Hi Georg,
I had the same error and I solved it by setting
parallel={'band':1}
in the calculator.

Best regards,
Ivano

On 11/08/2013 02:06 PM, Georg Kastlunger wrote:
> Hello,
>
> I have a somehow related question which might also help Sylvain i think.
>
> Im trying to calculate an fcc Au surface with a very dense kpoint 
> mesh. To do so I started with a kpts=(4,4,2) calculation to converge 
> the density and tried to fix this density (fixmagmom=True in 
> calculator) to calculate something like a band structure, as also 
> shown in the tutorial on band structure calculations. Unfortunately I 
> always get an error when I try to do so, which is related to the 
> domain decomposition done in the parallelization process:
>
> File 
> "/home/lv70174/georg/gpaw_inst_10428/lib64/python2.6/site-packages/gpaw/paw.py", 
> line 542, in initialize
> GPAW CLEANUP (node 173): <type 'exceptions.RuntimeError'> occurred.  
> Calling MPI_Abort!
> RuntimeError: Density reinitialization conflict with 'fixdensity' - 
> specify domain decomposition.
> Density reinitialization conflict with 'fixdensity' - specify domain 
> decomposition.
>     raise RuntimeError("Density reinitialization conflict "
>
> In a next step I tried to define the domain decomposition, which was 
> used for the inital calculation, by hand (parallel= {'domain': 
> (x,y,z)}), which led to a memory overflow in all cases.
> Before I now start to use a huge number of cores to get enough memory, 
> I wanted to ask if what I am doing is the right thing. I would be very 
> grateful for some feedback on and experiences with this.
>
> Best wishes,
> Georg
>
>
>
> On 11/07/2013 05:09 PM, Kristian Sommer Thygesen wrote:
>> Hi
>>
>> You should not do at sc DFT calculation using 200 k points. It should 
>> be possible to specify the k points in the transmission calculator 
>> based on an LCAO Hamiltonian obtained from a coarse sampling.
>>
>> Best regards
>> Kristian
>> ________________________________________
>> From: gpaw-users-bounces at listserv.fysik.dtu.dk 
>> [gpaw-users-bounces at listserv.fysik.dtu.dk] on behalf of Sylvain 
>> Tricot [sylvain.tricot at univ-rennes1.fr]
>> Sent: Thursday, November 07, 2013 4:14 PM
>> To: gpaw-users at listserv.fysik.dtu.dk
>> Subject: [gpaw-users] dense k point sampling
>>
>> Dear gpaw-users list,
>>
>> We are currently computing transmission coefficient maps on Fe(001) (12
>> layers including both principal layers and scattering region).
>> Calculations are done at no bias voltage. Results are fine for now and
>> transmission maps very similar to what is reported in the litterature
>> are found.
>>
>> BUT, very fine structures are expected in the transmission maps. Those
>> structures could only be observed by significantly improving the number
>> of k points.
>> Typical k points meshes found in the litterature are about 200x200x1.
>> But I cannot figure how such a dense k-grid could be possible since when
>> setting kpts=(24,24,1) in our example, the cluster computer is asking
>> for the whole 40GB of ram.
>>
>> So my questions are:
>> Is there an implemented way in GPAW to achieve such dense k-point
>> sampling using the transport calculator ?
>> Is it possible to split the calculation in smaller parts which would
>> compute only a given set of k-points, store them, and then reconstruct
>> the whole brillouin zone ?
>>
>> Thanks in advance for any thoughts and help.
>>
>> -- 
>> Sylvain Tricot
>> Ingénieur de Recherche
>> Institut de Physique de Rennes - UMR 6251
>> Département Matériaux/Nanosciences
>> Université de Rennes I
>> Campus de Beaulieu
>> Bat 11E
>> 35042 Rennes Cedex - France
>>
>> tel: +33 (0)2 23 23 69 06
>>
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>
>
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-- 

Ivano Eligio Castelli
Post Doc
CAMD
DTU Physics

Technical University of Denmark

	
Department of Physics
Fysikvej
Building 307
2800 Kgs. Lyngby
Direct +45 45253185
ivca at fysik.dtu.dk <mailto:ivca at fysik.dtu.dk>
http://dcwww.camd.dtu.dk/~ivca/ <http://dcwww.camd.dtu.dk/%7Eivca/>

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